1. Field of the Invention
The present invention relates to the production of a homogenous plasma. More specifically, the present invention relates to a device that uses microwaves for the production of homogenous plasma.
2. Description of the Prior Art
Various types of plasmas are generated using a wide variety of methods and devices. Plasma treatment is used, for example, for coating, cleaning, modifying and etching substrates, for treating medical implants, for inverting gases and in technology for purifying waste gases. The geometry of the workpieces to be treated ranges from flat substrates, fibers and webs, to any configuration of shaped articles. The size of the plasma chamber, and thus of the workpieces is limited. Materials in web form and fiber bundles can be processed only with difficulty.
Known devices have, for example, outer rings which can be constructed as a resonator. To feed the microwaves, use is made, inter alia, of waveguides and coaxial cables and, inter alia, of antennas, for example slots, as coupling points in the wall of the plasma chamber.
A disadvantage of the known devices are the formations of inhomogeneities in the in the plasma, particularly at high pressures and in relatively large plasma chambers and/or substrates.
The task therefore existed of generating a homogenous plasma and rendering possible homogenous plasma treatment.
It is proposed according to the invention to introduce the microwaves homogenously into the plasma chamber serving the purpose of processing via a cylindrical chamber and via coupling points in the cylindrical wall of this chamber. The plasma chamber is then to be constructed on the outside completely or partially covering the cylindrical wall of the chamber.